In the progressive era, which movement was the most important and which was the least?
The answer to this question is rather subjective. Factory workers would probably feel that the reforms in the workplace were really important. Those that care about fairness in politics may point to the reforms at all levels of government during the era. People that run powerful corporations would suggest that the antitrust legislation was not an important part of the progressive movement. Any answer to this question will be opinion-based.
From my perspective, the work of women to secure the right to vote was the most important part of the Progressive Movement. The hard work of the women's suffrage movement, which was considered radical at the time, resulted in the 19th Amendment to the Constitution in 1919. As hard as it is to believe, before this time, women did not have a voice in government. When you consider the important roles that women play in all levels of government today, it is not a stretch to opine that the women's suffrage movement was the most important reform of the movement. Without the 19th Amendment, you do not have a female running for president in the United States today.
The least important aspect of the progressive movement was a reform that was, ironically, also driven by women. The 18th Amendment, which grew out of the temperance movement, was a law that prohibited the manufacture, sale, and consumption of alcohol in the United States. Like many of the reforms of the progressive era, it was rooted in morality. Unlike many of the reforms, however, it was a major failure. The reason it should be considered the least important aspect of the progressive movement is because it did not significantly reduce the consumption of alcohol but did lead to problems like increased crime and corruption. The 18th Amendment was eventually repealed, which is the ultimate indictment of its failure.